Lightroom: If I trash all the old backup folders is it going to affect my catalog in any way?

In Lightroom 3 if you trash all the old backup folders is it going to effect the your catalog in any way? there are 61 backup folders in my lr catalog 61 seems redundant . It eats up a lot of space "162.91 GB on disk ". And yes I optimize my cat regularly.

Backups are just files, so they don't tie to your catalog and can be deleted when you feel you don't need them, anymore, if that's what you meant by saying "all old backups". But if you means "all backups" then that would not be a good idea since w/o a backup, if your catalog becomes corrupted for any number of reasons you could lose everything.

I usually keep the last few in case I don't discover the corruption right away and then a few back in time increasing the time period between, but remove most of the older ones.

For example, if I do a backup every week, I try to keep, a months worth of weekly backups, 6 months worth of monthly backups, and then one every year, and one whenever I upgraded LR last. And a few more at important stages when I might have completed an important event or trip.

I actually archive older photos and create a catalog containing their settings and then delete those photos out of my working catalog, so it's important to have a few catalogs back in time in case something happens to the archived catalogs.

To answer the question simply, each catalog LR creates is independently valid, so deleting a backup lrcat file will not impact the original from which it was created.

However, the fact that 61 backup folders total 162.91 GB on disk seems suspicious. That would be an average size of 2.5 GB. Is your primary lrcat file (not the Previews.lrdata folder/package next to it) in that ballpark? I'm guessing it'd be somewhat larger, since the backups have probably been getting bigger as the catalog grows (and the average is brought down by the earlier, smaller ones).

I ask because for all the catalogs I've seen, only a small handful are over 2 GB. One reason for the backups folder to be that big is that you've accidentally opened one of them and started using it so that it has built up a large preview cache.

If that's the case it explain the size, and it'd make that the advice of deleting them all be a bad data loss mistake.

I suspect the 555 GB figure includes the preview cache (which is large, but not backed up because it is strictly a derivative of the catalog and the referenced images and can be regenerated).

A 463K image catalog could definitely have an lrcat file in the > 2.5 GB ballpark, though, so that largely eliminates my concern that the large backup folder size is the result of accidentally opening a backup.

I would recommend keeping a few copies of the catalog. It's a bit better to keep them on a separate volume, of course (so you're protected from both file damage or drive failure).

It is a personal decision how many backup copies of a catalog one feels are needed to recover from corruption, but also maybe from accidentally removed images and such.

If you don't want to throw too many old copies away, you can always build ZIP archives of the backup folders. Catalogs zip really well, I notice an average of only 5% of the original size when using .zipx format.

FWIW, I've seen RAR based compressors get even better ratios by a significant margin. The largest catalog I've seen was 7 GB and zip compression reduced it to 1.2GB (less than the 8 or 10x reduction I often see) and RAR crunched it down to 126 MB (no typo). YMMV, but especially if you choose to push your catalogs through a cloud based backup (Dropbox, Mozy, CrashPlan, etc) it'll save you a lot of transfer time.

Compression of large files can take a long time, but if you even get close to those ratios, it'll pay off.

My catalog has 463525 photos since creating a new cat March 1 of 08.
the LRcat is 5.02 GB on disk run on a separate hard on my main machine.
The preview are what eats up the most space "Previews.lrdata 387.99 GB on disk "
I need them to access the images fast I can't wait for rerendering of a shoot of a 1000 images. I wanted to see of the trashing preview folders effects the the catalog.

Deleting the preview cache will probably result in a lot of churn while LR tries to rebuild it, re-rendering previews for any image that is shown with an out of date preview. Put shortly, it'll probably have a negative impact on performance.